Antigenic exposure at intestinal mucosal surface induces mucosal immunity at local as well as at distant mucosal surfaces such as lung and genital surfaces. Our hypothesis is that orally administered HIV-1 antigens that survive the low pH, bile salts and proteolytic enzymes of the stomach and gastrointestinal tract and exposed to M cells in Peyer's patches will induce strong mucosal immunity against the virus. Furthermore, mucosal immunity at the gut would induce immunity at distant mucosal sites, such as vagina or rectum. To prove this hypothesis we propose to use a non-cytotoxic (cytotoxic gene deleted) C. perfringens, a gram positive, anaerobic bacterium, as a vehicle to deliver HIV-1 proteins in large quantities to terminal ileum to induce strong mucosal immune responses. We have constructed a C. perfringens construct expressing large amount of HIV-1 -1 gag p24 proteins in the form of inclusion bodies. Furthermore, dendritic cells (DCs) beneath the mucosal surface in the Peyer's Patches (PPs) captured HIV-1 p24 when mouse PPs were exposed to recombinant C perfringens expressing HIV-1 in the lumen. While the recombinant C. perfringens can deliver large quantities of HIV-1 proteins to the PPs, enhanced intracellular uptake by DCs is expected to further stimulate T cell response. Protein transduction domains (PTDs) are known to enhance the delivery of numerous proteins to target cells, including DCs, both in vitro and in vivo. The PTD sequences PTDS and 8K have been shown to target proteins in DCs. Furthermore, to increase the breadth of immune responses it will be important include in the constructs other regions of gag, such as p17, which has been shown to carry antigenic determinants that elicit strong cellular and humoral immune responses. Thus, in the proposed study we will examine the effect of conjugation of PTDS and 8K on the intracellular uptake of HIV-1-1 gag p55 (containing p24 and p17 epitopes) expressed by recombinant C. perfringens and subsequent stimulation of T cell response in vitro. Finally, we will measure mucosal and systemic immune response to HIV-1-1 proteins ( with and without PTD) expressed in C. perfringens in mice and determine whether these clostridia recombinants alone or in a prime-boost delivery mode induces long lasting mucosal immunity. The proposed study provides a novel strategy to induce strong mucosal immunity against HIV-1 which can lead to development of an anti-HlV-1 oral vaccine due to its safety, low production cost and easy administration.